Serbian police officers of the Special Anti-Terrorist Unit pose for a picture in their base outside Belgrade October 8, 2014. When the killing of an unarmed black teenager by a white policeman in Ferguson, Missouri, in August sparked sometimes violent protests, the response of police in camouflage gear and armoured vehicles wielding stun grenades and assault rifles seemed more like a combat operation than a public order measure. Some U.S. police departments have recently acquired U.S. military-surplus hardware from wars abroad, but there are many law enforcers around the world whose rules of engagement also allow the use of lethal force with relatively few restrictions. But for every regulation that gives police wide scope to use firearms, there is another code that sharply limits their use. In Serbia, police may use measures ranging from batons to special vehicles, water cannon and tear gas on groups of people who have gathered illegally and are behaving in a way that is violent or could cause violence, but they may use firearms only when life is endangered. (Photo by Marko Djurica/Reuters)

Indonesian child jockey Egi, 8, poses for photographs as he participates in a traditional horse race marking Indonesia's 70th independence anniversary, in Bima, West Nusa Tenggara province, Indonesia, 08 August 2015. Horse racing is the traditional sport in the area and a cultural heritage which continues to be preserved by the people of Bima, a small city on the east side of Sumbawa island. Similar races also held in Sumbawa Besar regency and Dompu regency. (Photo by Mast Irham/EPA)

A person drags a suitcase as a boy clings to it on a square in front of a railway station ahead of the Chinese Lunar New Year in Qingdao, Shandong province, January 28, 2014. About 3.62 billion trips will be made during the 40-day Spring Festival travel rush, which started from January 16, reported Xinhua News Agency citing a government official. (Photo by Reuters/China Daily)

Wakhi nomad women milk yaks in Wakhan, Afghanistan. About 12,000 villagers live at an altitude of 4,500 metres in the harsh, desolate terrain. The Wakhi people live a simple, relaxed life with their livestock. (Photo by Eric Lafforgue/Barcroft Images)

A truck driver cleans the mirror of his decorated truck in Charsadda outside Peshawar, Pakistan October 18, 2016. (Photo by Fayaz Aziz/Reuters)

In this Tuesday, December 20, 2016 photo, Mohammad Ramzan, right, reacts while talking to The Associated Press with his young bride Saima in Jampur, Pakistan. Saima was given as a bride to the older man by her father so he could marry the groom’s sister, a practice of exchanging girls that is entrenched in conservative regions of Pakistan. It even has its own name in Urdu: Watta Satta, “give and take”. A mix of interests – family obligations, desire for sons, a wish to hand off a girl to a husband – can lead to a young teen in an a marriage she never sought. (Photo by K.M. Chaudhry/AP Photo)

Young women flash the victory sign in front of a bonfire as Turkish Kurds gather during Newroz celebrations for the new year in Diyarbakir, southeastern Turkey, on March 21, 2017. Newroz (also known as Nawroz or Nowruz) is an ancient Persian festival, which is also celebrated by Kurdish people, marking the first day of spring, which falls on March 21. (Photo by Ilyas Akengin/AFP Photo)

A man sits next to a damaged idol of Hindu goddess Kali which was taken out after its immersion in the river Ganges in Haridwar, India, March 29, 2017. (Photo by Danish Siddiqui/Reuters)